Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll MOD = 1e9 + 7;
const int inf = 1e9;
const ll INF = 1e18;
const double pi = 3.14159265358979323846;
#define rep(i,n) for(ll i=0;i<n;i++)
using Graph = vector<vector<int>>;
int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};

int main(){
	int h,w;cin>>h>>w;
	char g[h][w];
	int cnt=h*w-1;
	rep(i,h) rep(j,w){
		cin>>g[i][j];
		if(g[i][j]=='#') cnt--;
	}

	int dist[h][w];
	rep(i,h) rep(j,w) dist[i][j]=inf;
	dist[0][0]=0;
	queue<pair<int,int>> q;
	q.push(make_pair(0,0));

	while(q.size()){
		pair<int,int> now=q.front();
		q.pop();
		rep(i,4){
			int ny=now.first+dy[i],nx=now.second+dx[i];
			if(ny>=0&&ny<h&&nx>=0&&nx<w&&g[ny][nx]!='#'&&dist[ny][nx]==inf){
				dist[ny][nx]=dist[now.first][now.second]+1;
				q.push(make_pair(ny,nx));
			}
		}
	}
	cnt-=dist[h-1][w-1];
	if(dist[h-1][w-1]==inf) cnt=-1;
	cout<<cnt<<"\n";
}